One conventional data storage system employs write-through caching in which the data storage system acknowledges completion of write operations after the data storage system has written data to its backing store (e.g., disk drives). With write-through caching, there is certainty that the written data has reached its final destination.
Another conventional data storage system employs write-back caching in which the data storage system acknowledges completion of write operations after the data storage system has written data to its cache (e.g., dynamic random access memory or DRAM). Write-back caching provides better response time than write-through caching. Additionally, write-back caching may involve the use of a cache mirror (i.e., a second DRAM cache) to safeguard data which has been cached, but which has not yet been written to its backing store.